SNR of MP3, Split from Topic ID #96702 Options

[benski]

The LP noise floor is rather high- maybe -70dB under very good conditions. 12-bit sampling (RMS noise floor of -72dB) would be sufficient for LP use as long as your levels are right (peak signal above -6dB). (12-bit sampling was used for DV but hasn't seen any other widespread use).

The SNR of an MP3 is around 25-30dB. Does this mean that I only need to decode them to 6-bit PCM to capture all the details?

I am curious if anyone has ever done a detailed analysis of an LP's SNR in different frequency bands.

This post has been edited by benski: Aug 28 2012, 19:07

[pdq]

The SNR of an MP3 is around 25-30dB.

I don't know why you say that. The dynamic range of mp3 is obviously much greater than 30 dB.

I would be more inclined to describe mp3's deviation from the original as distortion rather than noise, because it is quite capable of rendering very quiet passages with very little added noise.

[pdq]

I'm a little confused as to what I am seeing. Was the original signal white noise at -50 dB with two notches?

[Arnold B. Kruege...]

I'm a little confused as to what I am seeing. Was the original signal white noise at -50 dB with two notches?

Kinda sorta. The original signal appears to have spectral characteristics that are stationary and have a very smooth, broad frequency distribution, such as we would see with a random noise signal.

Note that the signal was not at -50 dB. It is a signal that filled the FFT bins to the -50 dB point which is also dependent on the number of bins. The signal could have easily been just a few dB below FS.

When we are analyzing the performance of perceptual coders, the well-known and highly significant statistical differences between random noise and music make any results obtained that way very questionable. The example provided tends to support the previous statements of its author.

I used a recording of real-world acoustic music for my evaluations.

Also, I performed my evaluation at two significantly different bit rates, and compared the differences.

This post has been edited by Arnold B. Krueger: Aug 30 2012, 18:00